1. Field of the Invention
This invention relates to devices for converting a standard bicycle into a tandem bicycle.
2. Description of Prior Art
Tandem bicycles provide bonding between the captain (front rider) and the stoker (back rider), and are an enjoyable alternative to riding separate bicycles or children riding in bicycle seats. Also, a tandem bicycle safely teaches children how to ride a bicycle while an older rider maintains control. However, tandem bicycles are hard to store and transport and expensive, so attempts have been made to provide conversion kits for standard bicycles, or specialized frames that convert between single and dual rider bicycles.
However, existing products that adapt single-rider bicycles into tandem bicycle have one or more of the following problems:
a. The conversion frame pivots on the bicycle. This makes the combined frames unstable and difficult to steer. It is usually not strong enough to support an adult in the rear position.
b. Two bicycles are attached yielding a three or four-wheel tandem bicycle that is cumbersome, inefficient, and hard to maneuver.
c. The attached device acts more as a trailer.
d. The stoker is not required to pedal which means less participation/interaction between captain and stoker.
e. The stoker device only attaches at a single point, such as the seat post, yielding an unstable tandem bicycle that will yaw.
f. The whole frame is fully specialized for conversion to and from a single rider configuration, rather than using a standard bicycle. This is expensive.
The objectives of the present invention are to solve the above problems as follows:
1. Versatility. Provide a tandem adapter that attaches to a standard bicycle for a tandem ride, or left off for a solo ride.
2. Adjustability. Provide a tandem adapter that easily adjusts to fit a variety of bicycle frame sizes.
3. Ease of attachment and detachment. Provide a tandem adapter that can be setup by a person skilled in the art of bicycles, and then is easy to attach and detach by persons not skilled in the art.
4. Cost. Provide a tandem adapter that is a comparatively inexpensive alternative to owning both a single-rider bicycle and a tandem bicycle.
5. Storage. Provide a tandem adapter that requires less space than owning a single bicycle and a tandem bicycle.
6. Transportation. Provide a tandem adapter that allows single rider bicycles to be transported via standard bicycle racks. Attachment of tandem adapter takes place at destination.
These objectives are achieved by providing a tandem adapter frame that attaches to the back of a single-rider bicycle, transforming the bicycle into a tandem bicycle. The rear wheel of the single-rider bicycle is removed and the tandem adapter is attached to the single-rider bicycle at the seat post and the rear drop-outs, resulting in a highly rigid 3-point connection. The rear wheel is then mounted on the rear of the tandem adapter, transforming the single-rider bicycle into a rigid frame, two wheel, tandem bicycle with a rider in front (captain) and a rider in back (stoker). Both riders have pedals. An adapter axle assembly with sprockets on the lower front of the adapter frame serves two functions. It easily attaches between the rear dropouts of the single-rider bicycle using a standard axle and quick-release, and it transmits drive power to the rear crank without modifying the drive chain of the single-rider bicycle.